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Efeitos de agentes branqueadores nas propriedades de superfície de duas resinas compostas monocromáticas
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Objetivos: Avaliar e comparar o efeito de dois agentes branqueadores de uso domiciliário, peróxido de hidrogénio (PH) a 6% e peróxido de carbamida (PC) a 16%, na microdureza Vickers e na rugosidade de superfície de duas resinas compostas universais monocromáticas (Omnichroma e Vittra APS Unique).
Materiais e métodos: Foram confeccionados 60 corpos-de-prova em disco (8 mm × 2 mm), segundo a norma ISO 4049, distribuídos por cada resina em três grupos (n=10): controlo (sem branqueamento), PC a 16% e PH a 6%, durante 14 dias consecutivos, com armazenamento em água destilada a 37 °C. A microdureza Vickers foi determinada por indentação (1,961 N, 15 s) e a rugosidade avaliada com perfilómetro óptico (Sa, ASME B46.1-2013). Os dados foram analisados por rank-transformed ANOVA, Mann-Whitney e Kruskal-Wallis (p < 0,05).
Resultados: Observaram-se efeitos principais significativos do tipo de resina (p < 0,001) e do agente de branqueamento (p < 0,001), com interação significativa resina × tratamento (p = 0,003). A Vittra Unique apresentou microdureza globalmente superior à da Omnichroma. O efeito do branqueamento dependeu da resina: na Omnichroma, apenas o peróxido de carbamida a 16% reduziu significativamente a microdureza face ao controlo, não se observando efeito significativo com o peróxido de hidrogénio a 6%; na Vittra, ambos os agentes a reduziram, sem diferença entre si. A rugosidade não foi afetada pelo branqueamento (p = 0,432), dependendo apenas do tipo de resina (Vittra > Omnichroma; medianas de 1,830 μm e 0,752 μm, respetivamente; p < 0,001); todos os grupos excederam o limiar clínico de 0,2 μm.
Conclusão: Dentro das limitações de um estudo in vitro, o branqueamento domiciliário reduziu a microdureza de superfície de ambas as resinas compostas monocromáticas, de forma dependente do material, sem alterar significativamente a rugosidade de superfície.
Objectives: To evaluate and compare the effect of two at-home bleaching agents, 6% hydrogen peroxide (HP) and 16% carbamide peroxide (CP), on the Vickers microhardness and surface roughness of two universal monochromatic composite resins (Omnichroma and Vittra APS Unique). Materials and Methods: Sixty disc-shaped specimens (8 mm × 2 mm) were fabricated according to ISO 4049 and distributed for each resin into three groups (n=10): control, 16% CP, and 6% HP, for 14 consecutive days, with storage in distilled water at 37 °C. Vickers microhardness was assessed by indentation (1,961 N, 15 s) and surface roughness using an optical profilometer (Sa, ASME B46.1-2013). Data were analyzed using rank-transformed ANOVA, Mann- Whitney and Kruskal-Wallis (p < 0.05). Results: Significant main effects of resin type (p < 0.001) and bleaching agent (p < 0.001) were observed, with a significant resin × treatment interaction (p = 0.003). Vittra Unique showed overall higher microhardness than Omnichroma. The bleaching effect was resin-dependent: in Omnichroma, only 16% CP significantly reduced microhardness (6% HP did not differ from the control); in Vittra, both agents reduced it, with no difference between them. Roughness was not affected by bleaching (p = 0.432), depending only on resin type (Vittra > Omnichroma; medians of 1.830 μm and 0.752 μm, respectively; p < 0.001); all groups exceeded the 0.2 μm threshold. Conclusion: Within the limitations of an in vitro study, at-home bleaching reduced the surface microhardness of both monochromatic resin composites in a material-dependent manner, without significantly altering their surface roughness.
Objectives: To evaluate and compare the effect of two at-home bleaching agents, 6% hydrogen peroxide (HP) and 16% carbamide peroxide (CP), on the Vickers microhardness and surface roughness of two universal monochromatic composite resins (Omnichroma and Vittra APS Unique). Materials and Methods: Sixty disc-shaped specimens (8 mm × 2 mm) were fabricated according to ISO 4049 and distributed for each resin into three groups (n=10): control, 16% CP, and 6% HP, for 14 consecutive days, with storage in distilled water at 37 °C. Vickers microhardness was assessed by indentation (1,961 N, 15 s) and surface roughness using an optical profilometer (Sa, ASME B46.1-2013). Data were analyzed using rank-transformed ANOVA, Mann- Whitney and Kruskal-Wallis (p < 0.05). Results: Significant main effects of resin type (p < 0.001) and bleaching agent (p < 0.001) were observed, with a significant resin × treatment interaction (p = 0.003). Vittra Unique showed overall higher microhardness than Omnichroma. The bleaching effect was resin-dependent: in Omnichroma, only 16% CP significantly reduced microhardness (6% HP did not differ from the control); in Vittra, both agents reduced it, with no difference between them. Roughness was not affected by bleaching (p = 0.432), depending only on resin type (Vittra > Omnichroma; medians of 1.830 μm and 0.752 μm, respectively; p < 0.001); all groups exceeded the 0.2 μm threshold. Conclusion: Within the limitations of an in vitro study, at-home bleaching reduced the surface microhardness of both monochromatic resin composites in a material-dependent manner, without significantly altering their surface roughness.
Descrição
Dissertação para obtenção do grau de Mestre no Instituto Universitário Egas Moniz
Palavras-chave
Agentes branqueadores Cor única Microdureza Vickers Rugosidade de superfície